Aluminum Conductor Steel Reinforced (ACSR)

[HienN]

Dear all,

To get an assumption with voltage drop along the overhead power line, anybody suggests me the Reactance of this ACSR cable (240/39mm2).

Or any links, catalog, or documentation is appreciated.

Regards,

Hien

 

[davidbeach]

Conductor tables will get you the necessary properties; then you have to know the line geometery. Several references in the FAQ for this forum.

 

[HienN]

Davidbeach,

Here in our location, cable manufacturers only issued specification with (Resistance, take example for this conductor: R =0,1222ohm/km). But they dont issue the Reactance (X) normally.

For short-circuit calculation, reactance is necessary.

Thanks,

Hien

 

[7anoter4]

See Alcan Cable for Hawk type cable [240/40 ACSR] 7*2.7 mm steel; 26*3.4 mm alum.
AC [25oC, 60 Hz] Resistance =0.0366 ohm/1000ft; inductive reactance=0.0814 ohm/1000 ft. For further calculation [as davidbeach indicated] you have also GMR (Ft.) =0.0290.
1000 ft=304.8 m

 

[davidbeach]

That inductive reactance will be for a 1 foot spacing. There is another factor that has to be included based on actual spacing to get the total inductive reactance.

 

[jghrist]

Calculating Three-Phase Line Impedances in the Field
By: Mark Feller

http://www.appanet.org/newsletters/ppmagazinedetail.cfm?ItemNumber=17877&sn.ItemNumber=2108

gives the method of calculating, including a link to an Excel spreadsheet.

http://www.cable.alcan.com/NR/rdonlyres/BC388B10-A9C3-45B6-AA90-F5A9BA9D203D/0/ACSRweb.pdf

has electrical characteristics for US ACSR sizes.

 

[7anoter4]

A few remarks:
Actually XL[positive or negative reactance]=Xa+Xd.
Xa=0.99164/10^3*f*ln(1/GMR) ohm/1000 ft
Xa=it is the "inductive reactance" from catalog and it represents the inductive reactance at 1 ft spacing[ as explained already by davidbeach].
Xd=0.99164/10^3*f*ln(GMD) ohm/1000 ft
Xd is called the inductive reactance spacing factor.
Geometric Mean Radius[GMR]: There are magnetic flux lines not only outside of the conductor, but also inside. GMR is a hypothetical radius that replaces the actual conductor with a hollow conductor of radius equal to GMR such that the self inductance of the inductor remains the same. The GMR is given by manufacturer’s tables.
Geometric Mean Distance[GMD] replaces the actual arrangement of conductors by a hypothetical mean distance such that the mutual inductance of the arrangement remains the same.
GMD=(D12*..Dij*...Dnm) ^(1/n/m) is geometric mean[average] of reciprocal distances between conductors and has to be calculated.

 

[7anoter4]

I agree with jghrist that Alcan Table is according to B232 [USA].But I don't see any difference between B232 and DIN 48204. [Except the slight differences due to translation, may be].
See Simcat Table according to DIN 48204[for no.21 product]:

http://simcatco.com/products/Table.asp?id=2&kind=1

 

[HienN]

Thank you all,

Many useful was posted. But I still cannot catch the answer. What I have here is all about Copper (XLPE) cable information.

Regarding to this ACSR, any engineer who might faced this in the past? We use metric unit.

I have asked Electrical Vendor, Cable manufacturers... But unfortunatelly they dont have any information.

If you show me the formular (pls. note the referenced standard and book). See that, I need the evidence.

Lot of thanks to all of you,

Regards,

Hien

 

[davidbeach]

Any of the Power System Analysis books mentioned in faq238-1287. There are also various line parameter calculation programs out there. You have not provided enough information to calculate a reactance value (note: calculate, can't be looked up) as it is very dependent on the geometry of the line. You should be able to get the GMR of the cable (can't calculate that, has to be determined by test) or the self reactance value for unit spacing. In the ANSI world, the unit spacing is 1 foot, if you are using metric wire sizes I guess your unit spacing would be 1 meter. Then you need the spacing factor to add to the unit spacing inductance. Then to get the zero sequence impedance you have to factor in a bunch of other stuff, like neutrals and other grounded conductors.

In short, there isn't a single, simple answer.

 

[xxjohnh]

Try to get hold of the old Westinghouse books Transmission and Distribution and Distribution Systems, plenty of old copies around. Spacing is a big factor since this is overhead line.

 

[HienN]

Thank you all,

As said by Davidbeach,the spacing is 01 meter. ACSR cable (150 mm2. Any help?

Regards,

Hien

 

[7anoter4]

According to IEC 60909 ch.3 Three-phase overhead lines the inductive reactance (XL) for symmetrically twisted single-circuit and double-circuit lines are:
Single-circuit XL=w*miuo/(2*pi())*(ln(d/re)+1/(4*n)) in ohm/km
Double-circuit XL=w*miuo/(2*pi())*(ln(d*d'/(re*d"))+1/(4*n)) in ohm/km
where :
w=2*pi()*frq [frq=50 or 60 Hz]
miuo=4*pi()/10^7 H/m
re=equivalent conductor radius[mm] re=at/(2*sin(pi())/n) [approximately]
at=distance between 2 conductors on the last layer[mm] usually the aluminum conductor diameter and n=no. of strands in a bundle.
But for ACSR this is not accurate enough.
If we use this formula XL=2*PI()*frq*miuo/2/pi()*ln(d/re) then according to:
August Hochreiner "Symmetrische Komponenten im Drehstromsystemen" Berlin 1957 [see:

http://ester.nlib.ee/record=b1640399~S1*est

]
who gave experimental results as follow:
ACSR with 26 AL cond. in 2 layers re=0.809*r where r is the actual conductor radius.
ACSR with 30 AL cond. in 2 layers re=0.826*r where r is the actual conductor radius.
ACSR with 54AL cond. in 3 layers re=0.810*r where r is the actual conductor radius.
That is very close to GMR given by manufacturer catalog produce in USA [B232]
IF fqr=50 Hz then XL=0.06283*LN(d/re) ohm/km d and re both in the same units [mm or m]

 

[HienN]

Hi 7anoter4,

Thank you for your effort, I have tried this book "Transmission and Distribution Electrical engineering" issued by News 07’ edition. Please refer to the attachment for more details. Anyone knows where does this information coma from? It seems that bringing me back to the old time of 1986.

Firstly, I am still in doubt if I could use this as reference information. The designer wants to collect necessary information for their job.

Actually, I am not so lazy that just look up for an answer and avoid doing calculation. I am still reading 7aoter4 post.

Regards,

HienN

 

[7anoter4]

I know it is not important now but for the record only Xa and Xd formulas from my post of 24 Aug 09 15:58 are not correct for ohm/1000 ft. I translated this from ohms/mile incorrect and I apologize now.
Then correct it is so: Xa=0.383036/10^3*f*ln(1/GMR) ohm/1000 ft and Xd=0.383036/10^3*f*ln(GMD) ohm/1000 ft.
One could saw from Alcan Catalog [for HAWK type cable, for instance]:
Xa[inductive reactance]=0.0814 ohm/1000 ft and calculated for GMR=0.0290 ft per the last formula Xa=0.081367 ohm/1000 ft.
Also, the actual diameter of WAXWING type cable has to be 0.609 inches [and it is not 0.509 as shown in catalog-could be a printing mistake]

 

[HienN]

I think the most important thing is us.

Regards